中文摘要：

针对认知无线网络中的非实时通信业务，综合使用随机退避方式和控制中心调度方式，考虑两组授权信道，提出一种带有组间切换机制的混合式信道分配策略。基于认知用户数据分组数量及两组授权信道上分别传输的授权用户数据分组数量，建立三维Markov模型，导出认知用户的阻塞率、数据丢失率及平均延迟等性能指标表达式。数值实验和系统仿真的结果表明，随着退避时间的变化，不同性能指标间存在一定的折衷关系，通过选取最低的系统成本，给出退避参数的优化设置方案。

英文摘要：

Considering the non-real-time traffic in cognitive radio networks and two groups of licensed channels, comb- ing tiae methods of random back-off and control center schedule, a novel hybrid channel allocation strategy with channel group switching mechanism was proposed. Taking into account the total number of the cognitive packets and the numbers of the primary packets on each group channels, a three-dimensional Markov model was constructed, some cognitive user measures in terms of the blocking ratio, the packet loss ratio and the average delay were derived accordingly. Numerical results with analysis and simulation show that, as the back-off time changes, a tradeoff exists between different perform- ance measures. Therefore, by minimizing the system cost, the back-offtime can be optimized.